The present invention relates to a load-carrying rescue hook assembly intended to function at the end of a cable or rope, which is raised by a hoisting apparatus. The hook carries a load, which is typically attached to the hook in the form of a sling or similar attachment strap.
Known hook assemblies of this type comprise a hook member designed to carry a sling or similar load-bearing attachment strap. The sling or attachment strap is engaged to or disengaged from the load-bearing portion of the hook through a gap provided between one side of the hook and an opposed tip portion of the hook. For safety, a gate or latch of some type typically bridges this gap. In most cases, this gate is pivotally attached to the side of the hook opposite its tip and is spring loaded in such a manner that the gate is biased into the closed position to prevent accidental disengagement of the sling or strap.
Known hook assemblies of the above-mentioned type have considerable disadvantages. For instance, the spring used in the spring-loaded gate has a finite size constraint due to the dimensions of the hook and gate. This size constraint, in turn, limits the maximum allowable spring rate. At times when this type of hook is lifting a load, the load may oscillate a considerable amount. Though rare, these oscillations may cause the portion of the sling or attachment strap that is inside the hook to come into contact with the gate, overcome the spring force of the gate, and cause an accidental disengagement of the load in what is commonly referred to as xe2x80x9croll-outxe2x80x9d. In addition, if the gate is snagged by anything during use and the spring force is overcome, the gate can open. Thus, there is a potential for either an accidental disengagement of the load or accidental engagement of whatever snagged the gate.
To address the disadvantages caused by an accidental gate opening, some hooks employ a mechanism that locks the gate into the closed position in conjunction with spring-loaded retention. Operation of these gates usually involves a two-step operation, where the first step is to unlock a locking mechanism and the second step is to open the spring-loaded gate. When the gate is allowed to return to the closed position, the locking mechanism is automatically engaged and the process must be repeated in order to open the gate again.
Known hook assemblies that incorporate a locking mechanism are often difficult and cumbersome to operate. Because the operator of a rescue hook will often be wearing gloves, and because the hook may be used in adverse conditions such as cold weather, at night, in water, or a combination of the three, a two-step locking mechanism operation has proven to be difficult and can cost valuable time during a rescue operation. In addition, this operation must be repeated each time the gate needs to be opened, thereby increasing the number of times this difficulty must be overcome. Moreover, the locking mechanism of known hook assembles often requires a level of manual or digital dexterity that an operator may not possess when his or her hands are cold.
It is an object of this invention to provide a rescue hook assembly that utilizes a spring-loaded gate in conjunction with a locking safety mechanism to prevent accidental gate opening.
It is another object of this invention to provide such a locking safety mechanism that can be toggled from the xe2x80x9clockedxe2x80x9d to xe2x80x9cunlockedxe2x80x9d position or vice versa easily and with one motion, and that will remain in the xe2x80x9clockedxe2x80x9d or xe2x80x9cunlockedxe2x80x9d position as long as may be desired.
It is a further object of this invention to provide a locking safety mechanism that can be operated without requiring a high level of digital dexterity.
In particular, this invention provides a locking safety mechanism that operates separately from the spring-loaded gate, thus allowing the gate to be opened and closed numerous times while the locking mechanism is in the xe2x80x9cunlockedxe2x80x9d position, while not allowing the gate to open while the locking mechanism is in the xe2x80x9clockedxe2x80x9d position.
Further objects and advantages of the invention are set forth below or are apparent to those skilled in the art.
With these objectives in mind, the present invention provides a rescue hook assembly with a safety locking mechanism. The rescue hook is suited for, inter alia, helicopter search and rescue (SAR) operations. The rescue hook is comprised of a hook body having a curved, inner load-bearing surface at its lower portion and an attachment stem at its upper portion for attachment to a cable or rope of a hoisting apparatus.
An opening or gap into the curved, load-bearing surface is defined by a space between the hook""s tip end and the hook body opposite the hook tip. This gap allows the introduction of items into the load-bearing section of the hook body.
A spring-loaded gate is pivotally attached to the hook body and bridges the gap, and is biased by a spring towards the hook tip, thereby keeping the gap closed. The gate can be opened by applying pressure on the gate towards the hook body, and the gate will return to the closed position when the pressure is removed (e.g., when a load or sling is xe2x80x9csnappedxe2x80x9d into the hook). In order to keep the gate in the closed position when unwanted pressure might attempt to open the gate, this invention incorporates a safety mechanism. A sliding latch mechanism saddles the edge of the hook body and is located in such a way that it prevents the gate from opening when in a locking position.
The latch has two distinct positions: locked and unlocked. Each position is defined by the mating of the spring-loaded ball of a ball-detent plunger with an indentation on the inside face of the latch. When the indentation of the latch is mated with the ball-detent that corresponds to the locked position, the latch prevents the gate from opening even when pressure is applied to the gate. By applying pressure to the latch and sliding it, the latch moves away from the locked position until the indentation is mated with the ball-detent corresponding to the unlocked position. The gate is then allowed to freely open and close until the operator moves the latch back to the locked position.
Red and green pins made from fiber optic material or other suitable plastic are located in the hook body in such a manner that when the latch is in the locked position, the green pin is visible and the red is not. Likewise, when the latch is in the unlocked position, the red pin is visible and the green is not. The combination of the latch mechanism that can be easily moved between the locked and unlocked position along with color-coded indicators makes this rescue hook easy to operate with very little training.